I think it comes down to skill and hardware. ILM, Weta, Pixar & Digital Domain generally produce some amazing stuff because they have the sophisticated computers and talented CG artists. I think the artistry is particularly important.

Jurassic Park and Titanic still hold up pretty well today but they're not perfect. The lighting of the Brachiasaurus in the big reveal about 20 minutes in is a little too bright. Titanic's CG characters walk really stiffly like robots during the "take her out to sea, Mr. Murdoch" scenes. Among recent films, I'd have to give it to the Lord of the Rings movies -- just impeccable CG work used there. Why I think they did it so well was that they didn't rely just on CG -- physical models were heavily utilized as were old-school special effects and camera tricks.

I thought the ships in the new BSG looked reallly good. Those are CG aren't they? But usually I would agree.

I thought the werewolf cgi for 'An American Werewolf In Paris' was attrocious

Yes. It seemed like a Sci Fi Original that snuck into theaters.

I think Irreversible has some good CGI.
Not over used and blended with photographic & make-up effects.

yeah, I just read that, apparently the male appendage after the rape was CGI'd in.... who knew?

There are a couple "shaky" CGI shots in Jurassic Park, but I think they spent most of their time on the T-Rex. I've said it before in other posts, but I think the T-Rex from Jurassic Park is the most realistic CGI thing I've ever seen. In my opinion the Rex from Jurassic Park looked ten times better than the Rexes in Kong. Don't get me wrong--they looked fine in Kong, but the T-Rex looked REAL in Jurassic Park. At least for me it doesn't even have anything to do with the wow factor anymore. Maybe back then it was the first time I ever saw a "real" dinosaur and was blown away by it, but if I popped in Jurassic Park right now I'd say "there's a T-Rex" but if I popped in Kong I'd probably say "there are a couple T-Rex's that are obviously cgi and don't look nearly as good as the ones from Jurassic Park" I don't know...I still think that the entire first T-Rex attack scene in Jurassic Park is the finest and most realistic use of cgi ever. I haven't seen one in the last 13 years that's been better in my eyes.

I'm sorry, the CGI in T2 is not good by today's standards.

I agree, it is an excellent scene -- one of the greatest action set pieces in modern film IMO. But there was extensive use of animatronic models (anything closeup) and it took place at night, which is a lot easier for CGI as it hides details. In JP1's daytime CGI scenes, there is a overly bright appearance to the dinos. But that was 13 years ago. It looked phenomenal in 1993.

The best CGI I can recall seeing recently was in the Hulk.....

Exactly! If CGI is used to say, hide Superman's wires, or enhance an explosion, that's one thing. But when a character is nothing but computer generated, it looks more artificial than any stiff model work.

I agree. The Hulk and Van Helsing's werewolf looked ridiculous. I believe both those characters were 100% cgi. Then again, the Balrog in the Fellowship looked amazing and I'm sure that was 100% cgi as well. I guess I have the same question as the original poster...why do some movies (Lord of the Rings) have great looking cgi while other movies (Van Helsing) have terrible looking cgi? Does it simply have to do with cost or does it have to do with the people that are actually creating the computer generated characters?

Remember when Jeff Goldblum starts waving around the flare and then the T-Rex starts chasing him instead of following the flare? Do you know if that was an animatronic model or if that was cgi? When I look at that scene (and the movie in general) for the most part I can tell the difference between the models and the cgi. For example when the Rex first steps out of it's pen and roars that's cgi, but when it is about 6 inches away from the girl and Sam Neil that's animatronic. There are other pretty obvious examples too. I say they're obvious because in my opinion the cgi T-Rex shots look far better than the animatronic ones. For the most part whenever a dinosaur is moving exceptionally fast in that movie it's cgi. However, when it starts chasing Goldblum it's not moving overly fast on screen, but at the same time it looks really good, so that's one shot I've never known whether it's cgi or not.

I agree with your points, but on the whole, the entire scene is quite remarkable (flaws and all), the initial foot stomp (animatronic) sets the tone.

Another scene I could never figure out was when the T-Rex actually pushes over the truck. I know when it first bites the tire is cgi because of how fast it moved. I could tell it was animatronic when it was sitting on top of the car pushing the car and the kids into the mud just because of how it looked but I can't really tell when it actually pushes the car over. It looks like a model but at the same time I didn't think the model would have that much mobility. I suppose the car could have been rigged to just turn over, but if I remember correctly the T-Rex attempts to push it over and fails and then repositions itself and then pushes it over. In any event, yeah great action scene all around. Probably one of the best ever.

but even when the T-Rex spins the truck, there are quick moments where you can see that the animatronic's legs are pretty much locked to the ground. Also on some of the supplements of the scene, I remember that the truck was rigged to collapse/pulled around. Sorry to be nitpicking the scene, but the scene when viewed and evaluated under scrutiny (and on home video; dvd/laserdisc, where one can step frame through it) really is quite fascinating.

I'm sure it's a lot to do with cost, is a director willing to tell someone to redo a scene that looks bad if it'll cost an arm and a leg? Even within LOTR there is good CGI and bad CGI. The Balrog looks awesome, but that troll in the battle scene just before it looks pretty stupid at times. Or when Legolas is climbing around on the Oliphaunt, that looks pretty lame.

I'm sure you're right. Again, if I remember correctly there were a couple different T-Rex models. One full size model, one that was just the head and there might have been some others too. I remember hearing something about they waited until the very end of filming for Jurassic Park 3 to film the fight between the T-Rex and that spiny thing so basically it didn't matter if either one of the 2 full size models got beat up or destroyed because by then they were done with both of them. That's another good example...even though JP3 came out what 8 years after the first one I still think the effects (both cgi and animatronic) were better in the first one.

Why are some things different than other things?

As I recalled from a number of articles I read about JP, the full size, animatronic T-rex had no legs that touched the ground. He existed only from the tip of the nose to the tip of the tail and from the knee region and up. I'm fairly certain any shots showing T-rex feet touching the ground are totally CGI or CGI composited with the animatronic rex.

Reference material: Cinefex magazine, issue #55, August 1993, pages 61 and 65. Although a photo on page 60 shows a sculptor working a leg section from hip to foot, no photos in the entire article show the full size T-rex with complete legs. They're missing from the knees down. The most telling photo is on page 65 and shows the complete, full-size T-rex animatronic on the night shoot where the T-rex rolls over the JP tour vehicle. From the knees down, it is just mechanical elements and support structure.

FWIW, on pages 70 and 71 there are a series of photos of the sequence where the T-rex goes after Jeff Goldblum. It's CGI.

As for the original poster's question, there are quite a number of factors that affect the final result we see on screen. Others have posted some of those already. Besides the competencies of personnel from CGI operators to FX dept heads, there are budgets, various competitive and sometimes proprietary hard and software technologies, and a really big consideration...is time. It just takes time to render good CGI work properly.

The worst CGI in The Hulk, IMHO, is when they had Hulk trapped with the foam and Josh Lucas was going to inject him in the eye. It was horrible.

Seriously, there are shots that you can see in the documentary footage on the DVDs that are half-blue screen, that had me completely fooled. There's a scene in the Jedi Temple in ROTS that looks like a set, but the making-of material showed it to be half a set, with the rest blue screen.

I think all the good CGI that folks don't notice, makes them concentrate more on the not so good shots.

That and the need to bag on the prequels...

Agreed. The best CGI is the CGI you don't notice. When it starts to fall down is when we notice it.